Math Problem Statement

Solution

The given quadratic function is:

y=12x2+3x52y = \frac{1}{2}x^2 + 3x - \frac{5}{2}

We need to determine whether the function has a maximum or minimum value and find that value. Additionally, we need to find the value of xx at which this maximum or minimum occurs.

Step-by-Step Solution:

  1. Identify the form of the quadratic function: A quadratic function is generally given by: y=ax2+bx+cy = ax^2 + bx + c where a=12a = \frac{1}{2}, b=3b = 3, and c=52c = -\frac{5}{2}.

  2. Determine the direction of the parabola: The coefficient a=12a = \frac{1}{2} is positive, indicating that the parabola opens upwards. Therefore, the function has a minimum value.

  3. Find the vertex of the parabola: The vertex form of a quadratic function gives the minimum (or maximum) point. The x-coordinate of the vertex is found using: x=b2ax = -\frac{b}{2a} Substituting aa and bb: x=32×12=31=3x = -\frac{3}{2 \times \frac{1}{2}} = -\frac{3}{1} = -3

  4. Calculate the minimum value: Substitute x=3x = -3 back into the original function to find yy: y=12(3)2+3(3)52y = \frac{1}{2}(-3)^2 + 3(-3) - \frac{5}{2} y=12(9)+(9)52y = \frac{1}{2}(9) + (-9) - \frac{5}{2} y=92952y = \frac{9}{2} - 9 - \frac{5}{2} y=9218252y = \frac{9}{2} - \frac{18}{2} - \frac{5}{2} y=91852y = \frac{9 - 18 - 5}{2} y=142y = \frac{-14}{2} y=7y = -7

Conclusion:

  • The function y=12x2+3x52y = \frac{1}{2}x^2 + 3x - \frac{5}{2} has a minimum value.
  • The minimum value is 7-7.
  • This occurs when x=3x = -3.

Completing the Given Statements:

函数y有最小 (选填1: 大; 2: 小) 值, 值 = -7. 当x = -3时,随x的增大而减小。

Would you like any further details or explanations?

Here are 5 questions you can ask next:

  1. How do you find the vertex of a quadratic function in standard form?
  2. Can you explain how to convert a quadratic function to vertex form?
  3. What are the properties of parabolas in quadratic functions?
  4. How do you determine the axis of symmetry for a quadratic function?
  5. Can you explain the significance of the discriminant in quadratic equations?

Tip: When dealing with quadratic functions, always check the sign of the leading coefficient to determine if the parabola opens upwards (minimum value) or downwards (maximum value).

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Math Problem Analysis

Mathematical Concepts

Quadratic Functions
Vertex of a Parabola
Minimum and Maximum Values

Formulas

Quadratic function formula: y = ax^2 + bx + c
Vertex form of a quadratic function: x = -b / (2a)

Theorems

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Suitable Grade Level

Grades 10-12